Motor System: Basal Ganglia (Neuro Exam 2)

Front 1

Striatum

Back 1

- Caudate nucleus
- Putamen

Front 2

Corpus striatum

Back 2

- Caudate nucleus
- Putamen
- Globus pallidus

Front 3

Lenticular nucleus

Back 3

- Putamen
- Globus pallidus

Front 4

Basal ganglia

Back 4

- caudate nucleus
- putamen
- globus pallidus
- amygdala
- subthalamic nucleus
- substantia nigra

Front 5

Inputs to putamen

Back 5

motor and somatosensory cortex

Front 6

Outputs of putamen

Back 6

via globus pallidus:
1. primary motor cortex (M1)
2. premotor cortex
3. supplementary (M2)

Front 7

Basal ganglia circuit

Back 7

cerebral cortex->
basal ganglia->
thalamus->
cerebral cortex

Front 8

pathways out of GPi:
1. from ventral GPi?
2. from dorsal GPi?

Back 8

1. ansa lenticularis
2. lenticular fasciculus

Front 9

The magnocellular portion of substantia nigra is the pars _______ .

Back 9

compacta

Front 10

The pars _______ of the substantia nigra consists of smaller cells and is considered part of the GPi.

Back 10

reticulata

Front 11

Inputs to the caudate and putamen are primarily from the (1)______ and the neurotransmitter is (2)______.

Back 11

1. cerebral cortex
2. glutamate

Front 12

Input nuclei of basal ganglia.

Back 12

1. caudate nucleus*
2. putamen*
3. nucleus accumbens
(*caudate+putamen=striatum)

Front 13

Processing nuclei of the basal ganglia

Back 13

1. GPe
2. Subthalamic nucleus
3. ventral tegmental area

Front 14

Output nuclei of the basal ganglia

Back 14

1. GPi
2. Substantia nigra pars reticulata
3. ventral pallidum

Front 15

Output neurotransmitter of basal ganglia

Back 15

GABA

Front 16

Two parts of the substantia nigra

Back 16

1. pars compacta
2. pars reticulata

Front 17

The magnocelluar portion of the substantia nigra is the pars _____.

Back 17

compacta

Front 18

The pars (1)_____ of the substantia nigra is composed of smaller cells and is considered to be part of the (2)____, the major output nucleus of the basal ganglia.

Back 18

1. reticulata
2. GPi

Front 19

What are the two pathways out of the GPi:
1. from ventral GPi
2. from dorsal GPi

Back 19

1. ansa lenticularis
2. lenticular fasciculus

Front 20

Match the following (re: basal ganglia):
- direct pathway, indirect pathway
- movement suppression, movement initiation

Back 20

- direct pathway: movement initiation
- indirect pathway: movement suppression

Front 21

GPi projects to which thalamic nuclei?

Back 21

ventral anterior (VA) & ventrolateral (VL)

Front 22

Basal ganglia basic circuit

Back 22

cerebral cortex->
basal ganglia (striatum)->
thalamus (VA & VL)->
cerebral cortex

Front 23

Basal ganglia DIRECT pathway
1. diagram it
2. neurotransmitters at each step

Back 23

cerebral cortex-(glutamate)->
striatum-(GABA)->
GPi-(GABA)->
thalamic VA/VL-(glutamate)->
cerebral cortex

Front 24

Basal ganglia INDIRECT pathway
1. diagram it
2. neurotransmitters at each step

Back 24

cerebral cortex-(glutamate)->
striatum-(GABA)->
GPe-(GABA)->
STN-(glutamate)->
GPi-(GABA)->
thalamic VA/VL-(glutamate)->
cerebral cortex

Front 25

To what part of the basal ganglia do substantia nigra inputs project?

Back 25

Striatum (caudate+putamen)

Front 26

What subtypes of dopamine receptors are associated with the indirect and direct pathways in the basal ganglia?
Are these receptors inhibitory or excitatory?

Back 26

- indirect: D2, inhibitory
- direct: D1, excitatory

Front 27

How do D1 and D2 receptors exert their effects?

Back 27

D1 (excitatory) increases cAMP. D2 (inhibitory) decreases cAMP.

Front 28

What type of cell receives DA inputs in the basal ganglia direct pathway? Effect?

Back 28

- GABAergic medium spiny neurons (projection neurons)
- Excites them (D1 receptors), so they release GABA onto GPi/SNr.
- GPi/SNr then releases LESS GABA onto thalamic VA/VL.
- VA/VL then releases MORE glutamate onto motor cortex.
- MORE MOVEMENT.

Front 29

What type of cell receives DA inputs in the basal ganglia indirect pathway? Effect?

Back 29

- GABAergic medium spiny neurons (projection neurons)
- Inhibits them (D2 receptors), so they release less GABA at the GPe.
- Disinhibits GPe.
- GPe releases more GABA at STN.
- STN releases less glutamate at GPi/SNr
- GPi/SNr releases less GABA onto VA/VL
- Disinhibits VA/VL
- VA/VL releases more glutamate onto motor cortex
- MORE MOVEMENT

Front 30

What effects do dopamine have on the direct/indirect pathways (activate or inhibit)? On movement?

Back 30

DA activates the direct pathway (D1) and inhibits the indirect pathway (D2), both of which leads to increased movement.

Front 31

What type of cell receives dopamine inputs in the striatum? How are they different in the direct vs. indirect pathways?

Back 31

GABAergic medium spiny neurons, the projection neurons of the striatum. Direct have D1 receptors (excitatory). Indirect have D2 receptors (inhibitory).

Front 32

Chorea is typically caused by a lesion of the ____ of the basal ganglia.

Back 32

Caudate nucleus

Front 33

Athetosis is typically caused by a lesion of the ____ of the basal ganglia.

Back 33

Globus pallidus (or its projections)

Front 34

What's a key difference between Huntington's disease and levodopa induced dyskinesia of Parkinson's disease? (Hint: associated S/S)

Back 34

Levodopa induced dyskinesia is not associated with cognitive or behavioral sequelae.

Front 35

Hemiballismus is generally caused by a (1)[contralateral or unilateral?] lesion of the (2)____ or its projections.

Back 35

1. contralateral
2. subthalamic nucleus

Front 36

At the molecular level, Huntington's disease is associated with expansion of (1)____. This phenomenon is referred to as genetic (2)____.

Back 36

1. CAG (a trinucleotide repeat)
2. anticipation

Front 37

Match these disorders...
- Parkinson's, Huntington's, hemiballismus

with these anatomical structures:
- subthalamic nucleus, striatum, substantia nigra pars compacta

Back 37

Parkinson's: SNc
Huntington's: striatum
Hemiballismus: STN

Front 38

Describe the pathophysiology of hemiballism in terms of the circuit involved.

Back 38

- Lose STN glutamatergic input to the GPi
- Less GABA from GPi to VA/VL
- Disinhibits VA/VL
- VA/VL releases more glutamate at motor cortex
- Hyperkinetic movement disorder

Front 39

Hemiballism involves damage to the [direct or indirect?] pathway.

Back 39

indirect

Front 40

Parkinson's disease involves loss of dopaminergic neurons in the substantia nigra pars compacta. This affects the [direct/indirect?] pathway.

Back 40

BOTH direct and indirect

Front 41

True or false?

Parkinson's disease leads to degeneration of substantia nigra only, sparing other monoaminergic nuclei such as the locus ceruleus.

Back 41

FALSE. Locus ceruleus degenerates as well. PD pts. also have decreased levels of 5HT, another monoamine.

Front 42

Relation between the locus ceruleus and the substantia nigra

Back 42

- Locus ceruleus projects to the substantia nigra.
- Both are monoaminergic.
- Locus ceruleus: NE
- Substantia nigra: DA